Plug-in to allow trading replacing those buy/sell sub-forums?

Member

Most forums have just a sub-forum where everyone posts what he sells or buys. It does the job but quite cumbersome. Is there an add-on that takes the experience to the next level and makes easier. Something that's made especially for trading between forum users?
I did some searching but seems like there is next to nothing in that niche? Or I'm missing something?